What city became free under control of the league of nations?

The city of Danzig (now Gdańsk, Poland) became a free city under the control of the League of Nations following World War I. Established by the Treaty of Versailles in 1919, it was intended to provide a neutral territory for trade and to address the national aspirations of both Polish and German populations in the region. The Free City of Danzig existed until 1939, when it was annexed by Nazi Germany.